1. Field of the Invention
The invention relates to a switching element having moving contacts.
Such elements having reed contacts in a miniaturized form in a hermetically closed envelope have in late years been frequently used in modern telephone exchanges, computer systems and data transmisson systems.
In these switching elements the contact members are generally provided at the ends of resilient conductors and are enclosed in a space filled with a shield gas. The conductors consist of magnetic metal by which the contact may be opened or closed with the aid of coils or permanent magnets placed outside the envelope.
Stringent requirements as regards lifetime in an unloaded and in a loaded condition, and whether lightly or heavily loaded, are imposed on these elements, while the contact resistance must be low and constant throughout the lifetime of the element.
2. Description of the Prior Art
A coating consisting of a gold-cobalt alloy with a small quantity of carbon has been proposed as a contact surface material. This coating is electrolytically deposited from a solution of gold salt, preferably a gold cyanide complex and a cobalt salt. In such a bath an organic acid, for example, citric acid with its salt as a buffer, is also present. The combination of cobalt and cyanide provides for the low carbon content of the deposit which was found to result in very advantageous switching properties. The composition of the deposit is gold with approximately 0.3% Co and 0.5-1.5% C.
A drawback of this contact coating is, however, that the contacts equipped therewith have a tendency to sticking, resulting in a rather high percentage of rejects.